Metal–organic framework and carbon hybrid nanostructures: Fabrication strategies and electrocatalytic application for the water splitting and oxygen reduction reaction

With the rapid development of economy, the increasing energy crisis and environmental pollution urge us to develop sustainable and clean novel energy systems. Among them, the electrochemical energy conversion technology is considered as one of the ideal potential alternative energy systems, and the electrocatalysts play critical roles but are still challenging. Metal-organic frameworks (MOFs), thanks to their regular channels, atomically dispersed active centers, adjustable chemical and pore environments, have severed as promising electrocatalysts for electrochemical energy conversion. However, the relatively low conductivities and instabilities of MOFs limit their wide application in this field. In this case, fabricating hybrids of MOFs and carbon-based materials is an effective way to overcome above deficiencies. In addition, the synergistic effects between MOFs and carbons could optimize the electronic structures of active sites and promote the active surface areas, and thus improve the electrocatalytic performances of the composites. Herein, we outline the current development of MOF/carbon composites, including the fabrication methods of MOFs hybridized with various dimensions of carbon-based materials and the electrocatalysis utilization for water splitting, including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). Finally, the advantages and challenges of such catalysts are highlighted and future endeavors on the development of MOF/carbon composites for the HER, OER and ORR are discussed.